Automatic shut-off for winding apparatus



June 26, 1956 J, A. RUSSELL ET AL 2,752,452

AUTOMATIC SHUT-OFF FOR WINDING APPARATUS 2 Sheets-Sheet 1 Filed May 12, 1955 Q m\ 4 E w MW. a x P w I: m A mm H.|||l NH 0 MW Q04 J Fr a \W I w\ D\ June 1956 J. A. RUSSELL ET AL 2,752,452

United States Patent AUTOMATIC SHUT-OFF FOR WINDING APPARATUS John A. Russell and Frank X. Smith, Portland, Maine Application May 12, 1953, Serial No. 354,523

1 Claim. (Cl. 200-153) This invention relates to automatic shut-offs for winding apparatus and particularly to such apparatus for use in the rewinding of motion picture film.

While apparatus in accordance with the invention is adapted to many other uses, its novel features and advantages may be best appreciated in connection with the rewinding of motion picture film in theaters. In the rewinding of motion picture film, the reel on which the film is to be rewound, hereinafter sometimes referred to as the first reel, is driven as by means of an electric motor while the reel from which the film is unwound, hereinafter sometimes referred to as the second reel, is mounted so that it is free to rotate in response to the pull of the film after it has been connected to the first reel and the rotation thereof started by closing the circuit to the electric motor. The problem arises from the fact that, unless the first reel is stopped promptly after the second reel has been emptied, the free end of the film will be slatted about with consequent risk of damage thereto as long as the first reel continues to rotate. In commercial use, the problem is made serious due to the fact that the many duties of the operator or operators frequently make it either impossible or inconvenient to so attend the rewinding apparatus that rotation of the first reel can be stopped at the proper time.

This problem has been recognized and various brakes and other controls have been proposed to prevent injury to the film during the rewinding operation. Such proposals have not been satisfactory either due to their expense or due to the fact that they contemplated continuous contact with the moving film.

The principal objective of this invention is to provide a simple, elficient and economical control for the electric circuit to the rewinding motor by which the first reel is driven and this result is obtained by providing, in the circuit to the electric motor, a switch located conveniently adjacent the standard for the second reel and including a part, such as an arm, movable between a first position, in which the circuit is closed, and a second position, in which the circuit to the motor is open. Rotatable with the second reel is a pulley over which is trained an inextensible element, preferably in the form of a V-belt, having one end connected to that switch part and its other end connected to a suitably anchored spring by which the switch part is yieldably held in its first position. This action of the spring is counteracted during the rewinding operation by the frictional engagement of the element with the rotating pulley. As a consequence, the instant the end of the film being unwound is pulled free from the now empty second reel, the spring becomes effective to cause the switch part to be pulled into its second position, thus breaking the circuit to the motor. Because of the nice balance that must exist between the spring and the force exerted by the pull of the film, there is employed adjustable means for varying the action of the spring to ensure accurate control of the motor circuit.

In the accompanying drawings, there is shown an illustrative embodiment of the invention from which other 2,752,462 Patented June 26, 1956 objectives of the invention and its novel features and advantages will be readily apparent.

In the drawings:

Fig. l is a side view of film rewinding apparatus illustrative of that with which the invention is concerned;

Fig. 2 is a view, on an enlarged scale, of the reel from which the film is unwound and showing the shut-off mechanism as viewed from the left hand end of the apparatus as shown in Fig. 1;

Fig. 3 is a corresponding fragmentary view of the reel onto which the film is rewound showing the brake therefor; and

Fig. 4 is a fragmentary section taken along the indicated lines 4-4 of Fig. 3.

The invention is herein discussed with reference to the rewinding of motion picture films in theaters where, typically, standards 5 and 6 are clamped to a shelf or bench 7 in spaced relation to each other. The standard 5 may be of any desired type and its function is to support the reel 8 on which the film 9 is to be rewound from the reel 10 mounted on the standard 6.

The reel shaft 11 of the standard 5 is shown as provided with a pulley 12 connected by a belt 13 to the pulley 14 of the electric motor 15 shown as bolted to the under surface of the bench 7.

The standard 6 is generally similar to the standard 5 in that it has a pulley 16 on its reel supporting shaft 17, said pulley being shown as of relatively small size. Adjacent the standard 6 and conveniently secured thereto, there is a switch generally indicated at 18 in control of the circuit to the motor 15, the cable being indicated at 19. While the switch 18 may be of other types, it is preferably a toggle switch having a relatively long arm 20, thus to afford a degree of mechanical advantage for reasons that will subsequently be apparent.

Trained over the pulley 16 of the standard 6 is a belt 21 preferably of Vshaped section. The belt 21 is connected at one end to the switch arm 20 while its other end is connected to the control comprising the spring 22 and tension regulating means such as a turnbuckle 23. The control is anchored in any suitable manner as by securing the spring 22 to the lower part of the standard 6.

The switch arm 20 is shown in its circuit opening position and it will be apparent that the spring 22 is operative to yieldably maintain the switch arm in that position.

When film 9 is to be rewound from a full reel 10 after use and onto an empty reel 8, to thus prepare the film for re-use, the reel 10 is mounted on the shaft 17 of the standard 6. In the embodiment of the invention shown in the drawings, the reel 8, as viewed in Fig. 1, rotates in a clockwise direction and as the pull of the spring 22 is in a clockwise direction relative to the pulley 16, the film 9 is connected to the reel 8 in the manner shown, thus to cause the reel 10 to rotate in a counterclockwise direction whereby the friction developed between the belt 21 and the pulley 16 is a force counter to the pull of the spring 22.

When the tension of the regulating means 23 is properly adjusted, the pull of the film 9 being rewound is effective to offset the pull of the spring 22, but when the film 9 comes free from the reel 10, the spring 22 becomes immediately operative to pull the switch arm 20 into its circuit opening position.

There is shown a brake operative to stop the shaft 11 of the standard 5 once the automatic shut-off has opened the circuit to the motor 15. This brake, as may best be seen in Figs. 3 and 4, consists of a disc or drum 24 on the shaft 11 which the shoe 25 on the arm 26 engages. The arm 26 is pivoted as at 27 and yieldably urged into braking position by the spring 28.

The brake in control of the shaft 11 may be of any other type but that shown is commonly used to prevent the overrunning of the reel 10 as it is rotated by the pull of the film being rewound, a function also accomplished by automatic shut-offs in accordance with the invention.

With an automatic shut-off in accordance with the invention, it is only necessary for the operator to manually move the switch arm 20 into its circuit closing position after the film 9 has been properly connected to the reel 8 and to hold the switch arm 20 momentarily in that position until rewinding is started. Thereafter, he may attend to other duties since the circuit to the motor 15 is instantly opened when the film 9 pulls free from the reel 10.

What we therefore claim and desire to secure by Letters Patent is:

In combination, a supporting standard on which is carried a rotatable shaft and pulley, an electric switch mounted on the standardand provided with a switch control arm movable between switch closing and switch opening positions, a flexible member connected at one end to said control arm, a spring having one end anchored to the standard, and a turnbuckle interposed between the spring and the flexible member and having one end attached to the free end of the spring and its other end attached to the free end of the flexible member to vary the tension of the spring, said spring yieldably pulling the flexible member in a direction to move said control arm in switch opening direction, said flexible member being trained over said pulley and frictionally engaging therewith to overcome the action of said spring when the shaft is rotating in a direction to exert a pull on said member opposite to that exerted by said spring.

References Cited in the file of this patent UNITED STATES PATENTS 1,144,362 Kempff et a1 June 29, 1915 1,632,968 Hipps June 21, 1927 1,814,739 Preddy July 14, 1931 2,132,024 Goldberg Oct. 4, 1938 FOREIGN PATENTS 419,944 Germany Oct. 12, 1925 

